Zearalenone and its derivatives are the basic Resorcylic Acid Lactone (RAL) compounds used as the starting materials for the compounds of the present invention. Zearalenone may be prepared by culturing the zearalenone producing strain of Gibberella zeae as taught in U.S. Pat. No. 3,196,019, incorporated herein by reference. Zearalenone and its ring-opened and other derivatives have been reviewed in the literature. Shipchandler, Heterocycles, 3(6):471-520 (1975) and Hidy et al "Zearalenone and Some Derivatives: Production and Biological Activities", Adv. Appl. Microbiol., 22:59-82 (1977).
Zearalenone has been chemically modified to form numerous derivatives. U.S. Pat. No. 3,239,348, incorporated herein by reference, discloses a method for producing zearalenol from zearalenone by reducing the ketone carbonyl group. U.S. Pat. No. 3,239,345, incorporated herein by reference, discloses a method for producing zearalanol from zearalenone and zearalenol by reducing the ketone carbonyl group and/or the macrocylic ring double bond.
These compounds have generally been used to improve growth performance in ruminants and to reduce the severity of vasomotor symptoms associated with menopause in women. These compounds, however, have often been difficult to administer or have had undesirable side effects. In addition, these compounds have often not been as highly effective for the intended purpose as desirable. There is, therefore, a continuing need for new compounds that can reduce problems with administration, lessen the toxic and other undesirable side effects, and improve upon the efficacy of such compounds. One method for meeting these needs has been to produce various derivatives, particularly ester derivatives or compounds that give a biological response similar to the ester derivatives, of the compounds in an effort to improve the efficacy of the compound and lessen any possible side effects.